Angus Bevan of Integrated Woodland Management recently undertook a Plantations on Ancient Woodland Sites (PAWS) assessment of Glenan Wood funded by Woodland Trust. You can read the full report here.
Restoration of plantations on ancient woodland sites is now considered to be good forestry practice. The aim is to restore areas of ancient woodland that have been converted to plantations of non-native species, or are threatened by invasive, non-native species, by harvesting the exotic trees and re-instating native woodland over an appropriate period of time.
Angus surveyed 138 hectares of Glenan focussing on areas with a probable PAWS interest, based on the Native Woodland Survey of Scotland and the first edition O.S. map from 1840.
The assessment identified three of the five zones within Glenan as ‘threatened’ (unlikely to be lost in the short term, given current conditions, but long term survival is doubtful without intervention) and recommended short, medium and long term management priorities.
In the short term, invasive rhododendron control was highlighted as key. The rhododendron population in Glenan woodlands should be addressed as a priority to prevent further colonisation.
Conifer removal was also identified as key, and all conifers should ultimately be removed from these woods, as they will compete with the native trees for light and root space, and continue to colonise more ground through the establishment of seedlings. Priority should be given to the eradication of Western hemlock. This species is an aggressive coloniser, and several mature specimens are present. Western Hemlock will soon grow through the canopy of the oak and shade it out (see picture below).
Deer control was identified as another priority. The assessment found clear impact from deer browsing deer in most parts of the woods, with seedling establishment entirely prevented, and the lack of native saplings or pole stage trees indicates that this has been the case for decades. The domination of the ground flora by grasses and unpalatable species such as bracken is a further effect of sustained browsing pressure.
In the medium term, bracken management was identified as important. Much of the poorer ground that is currently dominated by bracken should recover a greater level of diversity if seedling establishment is allowed by the reduction of deer browsing pressure. The increase in shade will suppress the vigour of the bracken and allow competition from other ground flora. But regular bracken bashing is needed as well.